Harmonies of Heaven and
Earth. The Spiritual
Dimension of Music from Antiquity to the Avant-Garde. London:
Thames & Hudson,
1987; Rochester, Vt.: Inner Traditions; also published in French, German, and Japanese; partly published in Spanish.

Upstate Cauldron: Eccentric Spiritual Movements in Early New York State.Albany: State University of New York Press, 2015.

Symbols in the Wilderness: Early Masonic Survivals in Central New York. Co-authored with Christian Goodwillie. The Upstate Institute at Colgate University and the Richard W. Couper Press of Hamilton College, 2016.

Macrocosmos, Microcosmos y Medicina: Los Mundos de Robert Fludd. Girona: Ediciones Atalanta, 2018. [In Spanish] Forthcoming in English as Macrocosm, Microcosm, and Medicine: the Worlds of Robert Fludd.

Harmony of the Spheres.
A
Sourcebook of the Pythagorean Tradition in Music. Rochester, VT:
Inner
Traditions International, 1993; also published in Spanish (Girona: Atalanta, 2009), with illustrations and a new introduction.

The Hermetic Brotherhood of
Luxor. Historical
and Initiatic Documents of an Order of Practical Occultism. Co-edited with
Christian Chanel and John Patrick Deveney. York Beach: Samuel Weiser,
1995). Also published in French
and Italian.

The Starlight Years: Love and War at Kelmscott Manor, 1940-1948. The Paintings, Drawings and Writings of Edward and Stephani Scott-Snell/Godwin. Stanbridge: Dovecote Press, 2015. http://www.amazon.com/The-Starlight-Years-Kelmscott-Manor/dp/0992915112

Johann Valentin Andreae,
The
Chemical Wedding of Christian Rosenkreutz.Grand Rapids: Phanes
Press, 1991. Reissued in Rosicrucian Trilogy: The Three Original Rosicrucian Documents in New English Translations. Translation of the Fama Fraternitatis by Christopher McIntosh and Donate Pahnke McIntosh; translation of the ConfessioFraternitatis and Chymische Hochzeit by JG. Newburyport: RedWheel/Weiser, 2016.

65. "Julius Evola: A Philosopher for the Age of the Titans." Tyr 1
(2002): 127-142. Revised and reissued as "Who Was Julius Evola, Really?" New Dawn 162 (May-June 2017): 60-68. Also published in German in Gnostika.